I commend to the attention of New York concertgoers several events of the experimental, "downtown," woah-dude variety. On Friday and Saturday, members of the ne(x)tworks ensemble will present a new piece by Joan La Barbara, in collaboration with the Nai-Ni Chen dance company. Then, on Sunday, some of those same players will join Elliott Sharp, Jenny Lin, and other edgy notables in a tribute to the pioneering electronic composer James Tenney, a Project Room event in the East Village. The crowd favorite is almost certain to be Tenney's astonishing 1961 piece Collage #1, aka "Blue Suede," after which you'll never listen to Elvis Presley in the same way again. (You can hear it on a New World Records Tenney compilation.) Also, the Bamberg Symphony plays two concerts at Lincoln Center. On Sunday, they combine Ligeti's Atmosphères and Etudes (Pierre-Laurent Aimard pianifying) with Beethoven's Emperor and the Adagio from Mahler's Tenth.